You need to find your existing Support ID.
You can find your Support ID from within CAD by opening the General Preferences screen:
F/X Admin ribbon
Any of the F/X pull-down menus (F/X Admin, F/X Site, F/X Planting, F/X Irrigation, or F/X Details
Several toolbars (FX Admin toolbar pictured)
or type *FXPreferences in the Command line
Make sure the General option is selected.
Your Support ID is located in the License Information section of the General Preferences screen, as shown in the image to the right.